This invention relates generally to die casting apparatus and, more particularly, to a mechanism employed in conjunction with a die casting apparatus for mechanically removing the sprue from a completed casting.
Cast articles are formed by injecting molten casting material into a mold cavity defined by interfitting dies. When producing cast articles by such a process, the casting generally has a sprue or gate of excess material formed thereon at the point where the molten material is injected into the mold cavity. Since the sprue is not an intended element of the completed casting, it must be removed.
Removal of the sprue can be achieved by removing the casting from the dies and subsequently trimming off the sprue manually or by separate operation at another machine. In the prior art, there are a number of die casting machines incorporating mechanisms which will remove the sprue at the dies while the dies are opening.
A number of machines employ hydraulically or pneumatically operated degater knives for shearing the sprue. Illustrative of these machines are Boberg U.S. Pat. No. 3,916,986, Halko et al U.S. Pat. No. 3,845,531, Scott et al U.S. Pat. No. 3,844,335, Fisher U.S. Pat. No. 3,256,572, Pouell U.S. Pat. No. 3,191,246, Mills U.S. Pat. No. 2,946,102 and McGarigal U.S. Pat. No. 2,612,666.
Other patents disclose the shearing of sprues by the dies themselves as the dies are moved apart to release the casting. These include Sunday U.S. Pat. No. 2,995,788 and Pouell U.S. Pat. No. 2,821,756.